<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>媒体查询</title>
</head>
<style>

    @media screen and(max-width:500px){
        body{
            background-color: #bfa;
        }
    }

</style>
<body>
    <div id="app">
        999
    </div>
</body>
</html>
